From: "H. Peter Anvin" <hpa@zytor.com>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Yinghai Lu <yinghai@kernel.org>,
"kexec@lists.infradead.org" <kexec@lists.infradead.org>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: How does kdump deal with trampoline allocation?
Date: Mon, 27 Dec 2010 16:13:55 -0800 [thread overview]
Message-ID: <4D192BC3.8040802@zytor.com> (raw)
In-Reply-To: <20101228000651.GB4142@redhat.com>
On 12/27/2010 04:06 PM, Vivek Goyal wrote:
> On Mon, Dec 27, 2010 at 12:31:20PM -0800, H. Peter Anvin wrote:
>> Hi guys,
>>
>> I'm planning a major overhaul of the trampoline allocation in x86, and
>> I'm trying to understand how kdump deals with it. The trampoline has to
>> be allocated in low memory (< 1 MiB) and obviously that doesn't include
>> the kdump area at all.
>
> Hi Peter,
>
> Kdump has the concept of backup area. We backup the contents of first
> 640KB of physical RAM in kdump reserved area and then allow kdump kernel
> to use first 640KB of memory. So any trampoline allocation can be done
> in low memory area without overwritting the contents of first kernel.
>
OK, that's straightforward. That presumably means that the low 640K is
marked unused in the memory map that memblock sees during early startup.
That fits very cleanly with the patches I'm doing.
Thanks!
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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next prev parent reply other threads:[~2010-12-28 0:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-27 20:31 How does kdump deal with trampoline allocation? H. Peter Anvin
2010-12-28 0:06 ` Vivek Goyal
2010-12-28 0:13 ` H. Peter Anvin [this message]
2010-12-28 7:40 ` Eric W. Biederman
2010-12-28 20:11 ` H. Peter Anvin
2010-12-29 4:13 ` Eric W. Biederman
2010-12-29 6:25 ` H. Peter Anvin
2010-12-29 8:37 ` Eric W. Biederman
2011-01-03 5:01 ` Vivek Goyal
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